The present invention relates to a spring bushing for miniature plug-in connectors, having at least one housing chamber in a bushing housing, for accommodating a one-part contact spring, the contact-giving spring tongues of which are bent out of a flat sheet-metal punched part, at least on one side, without coverage. The one end of the sheet-metal punched part, a crosspiece that carries the spring tongues, forms a fixed connector, and the other free end forms the accommodation region for a contact blade.
The Prior Art
Usually, contact springs are punched out of a plate, in U shape, whereby the two U-shanks, which form spring shanks, are subsequently rotated relative to one another with regard to the U-crosspiece, thereby causing the U-shanks to lie precisely opposite one another and to form the accommodation for a contact blade. The punching scrap and the production effort and expense are accordingly high. Measured by the available starting material of sheet metal for punching, the punching scrap reduces the possible current carrying capacity of a contact spring. Furthermore, the region in which the U-shanks are rotated relative to one another is not available for contacting with the contact blade and for the production of spring forces, and this unavailability regularly causes the contact springs and therefore the spring bushings to become very long.
A spring contact for electronic components is previously known from DE 87 10 419 U1, in which the spring shanks are uncovered relative to one another, in that one of the spring shanks is cut out of the plane of the other spring shank and bent out. The crosspiece carries contact pins for circuit board assembly. In this way, the punching material is utilized in optimal manner. But this spring contact, too, has relatively long spring shanks, and these long spring shanks have a negative effect on the tolerances in the plug-in depth, the plug-in reliability of the blade contact, and the current carrying capacity, particularly for applications in multi-point miniature bushings, such as female multi-point connectors. Furthermore, a great plug-in depth also requires a correspondingly great construction height of the bushing and of the counter-plug part.
A one-piece pin structure of an electrical connector terminal for affixing electrical or electronic components on a circuit board is also known from DE 93 10 600 U1, which has a clamp holder segment, a carrier segment, a retention segment, and a connection pin segment, and thereby has a very long construction length, in total. The clamp holder segment is formed by two spring arms, in order to engage with and clamp a counter-contact pin of a component. The spring arms have a common base, which is connected with the carrier segment, whereby the two arms branch off from one another from there. A shorter, center arm is cut out of a sheet-metal part for this purpose, and bent, in such a manner that the counter-arm whose two outer arm parts are connected at the free end is formed from the remaining sheet-metal segment.
Furthermore, a plug-in sleeve for circuit boards is known from DE 197 24 581 A1, which contains clamping elements in a housing, for insertion of counter-blades. A clamping element is formed from sheet metal, as a one-piece punched part. The clamping element contains two flat arms that lie in a common plane, between which a tongue is disposed, separated by a slot, in each instance. The tongue is connected with a crosspiece that connects the two arms, and bent away so that it runs upward out of the plane of the arms in its region directly adjacent to the crosspiece, and subsequently comes close to the top side of the arms again. In a straight-line extension of the arms, two projections to be pressed into the circuit board are molded on, on the far side of the crosspiece. Shoulders on the outside edges of the arms delimit the push-in path into the housing. This clamping element, too, still possesses a relatively great plug-in depth, in comparison with its width, which affects the length of the entire plug-in sleeve.
Finally, DE 202 03 083 U1 discloses a frame-like spring contact for applying a circuit board and for accommodating a contact blade. This spring contact is also produced from a one-piece metal sheet by means of punching and bending, and has at least one pair of contact arms that lie opposite one another. This contact possesses a very small insertion depth, but is relatively great in volume, in total, because of its frame-shaped structure, and therefore is unsuitable for multi-point contact bushings in the standardized female multi-point connector raster dimension (2.54 mm). With this spring contact, the two ends of the punched sheet-metal part are formed into fixed contacts in the form of solder tags or surface mount device (SMD) contacts for the circuit board, and the spring arms are cut out in opposite directions, from the center of the punched sheet-metal part towards the fixed contact ends, whereby two crosspieces carried by edge ridges remain standing as an insertion aid for the contact blade. The punching and bending tool for the production of this spring contact therefore becomes relatively complicated.